Utility control systems in Substation Automation Systems (SAS) and control centres in a power system network together serve to monitor, supervise, control, and protect the power network to economically provide high quality electricity in a reliable manner. The operation of the power system network can be improved by ensuring a higher degree of integration of control centre applications and SAS applications. The integration requires exchange of data between SAS and the control centre. This data exchange relates to both—the system configuration data used at the time of system/application engineering and integration, and the live data used at systems' runtime.
SAS and control centres use different standards, according to which the corresponding data is modelled. In particular, the two International Electrotechnical Commission (IEC) standards used are IEC 61850 at the SAS, and the Common Information Model (CIM) of IEC 61970 at the control centres.
Exchange of data between such systems is essential if the systems are to be integrated or interoperated. However, the data modelled, based on a particular standard is not accessible to systems that use data modelled, based on another standard. This limits interoperability between systems that use data modelled, based on different standards. Data exchange between such systems requires data models to be mapped between the two standards.
Generally, the amount of data to be converted is large. This makes the mapping of data between the standards a tedious task. Further, the understanding and preservation of the involved semantics makes the task of data mapping complex. The mapping requires a syntactically and semantically accurate conversion. As a result, the conversion of data from IEC 61970 to IEC 61850, and vice versa, is difficult due to the complexity of the data models in the two standards.
IEC 61970 defines an Application Program Interface (API) for an Energy Management System (EMS). IEC 61970 defines, amongst others, a data model for control centre systems/applications. A Common Information Model (CIM) specifies the semantics of the API. The CIM is an abstract model that represents all the major elements in a control centre system, that are typically needed to model the operational aspects of the control centre system. The CIM can be used in a variety of applications to enable integration. In particular, the CIM is used wherever a common power system model is needed to facilitate interoperability and plug compatibility between applications and systems independent of any particular implementation.
The IEC 61850 is a standard that defines, amongst others, a data model for Substation Automation systems (SAS), and is a standard for communications within a substation. IEC 61850 contains a device model, which describes the function allocation as well as the properties of each physical device. IEC 61850 provides a data model for Logical Nodes (LN). LNs are the atomic functional building blocks of an SAS and contain the data and attributes of the respective elements. IEC 61850 also defines the Substation Configuration Language (SCL), an eXtensible Markup Language (XML) Schema, to configure the substation and for file exchange of configuration data.
Efforts have been made to enable the conversion of data in one standard to another. U.S. patent application No. ‘US2002059566’, titled ‘Uni-level description of computer information and transformation of computer information between representation schemes’ provides a system and method for transforming selected computer information described by using one model of data representation to computer information described by using a second model of data representation. The transformation involves expressing the selected computer information in a uni-level description scheme. The uni-level description scheme uses basic structures that represent the selected computer information, with reference to a generic set of abstractions applicable to representation schemes with different model structures. Following this, the selected computer information is transformed and expressed in the uni-level description to the second representation scheme.
The article by T. Kostic et al entitled “Towards the formal integration of two upcoming standards: IEC61970 and IEC61850”, Proc. of 2003 LESCOPE conference, Montreal, May 7-9, 2003, pp. 24-29, describes an attempt to create a bi-directional mapping of IEC 61850 to IEC 61970 data representations for a limited number of elements of a substation. To this end, in addition to the Unified Modelling Language (UML) based representations that are an integral part of the IEC 61970, a UML model of the IEC 61850 was developed and a UML model of the mappings between the two standards was built.